Common Lisp: An interactive approach
Electronic book introducing Common Lisp.
Home – the Common Lisp Cookbook
A cookbook of Common Lisp code.
Read Loving Common Lisp, or the Savvy Programmer's Secret Weapon | Leanpub
Book that introduces Common Lisp.
Common Lisp: A Gentle Introduction to Symbolic Computation
Free book that should be a good introduction to Common Lisp for many people.